Among families and friends

YOUNGER readers ought to enjoy the antics of Angel's Mother's Wedding, by Judy Delton, illustrated by Margot Apple (Houghton Mifflin, Boston, $12.95, 166 pp., ages 8 to 10) - one of the few books for this age group that treats a family in transition in an appealing, reassuring way. As Angel prepares for her mother's wedding, she has some amusing concerns - about the cake, the invitations, the wedding dresses - and some more fundamental ones, especially about the coming honeymoon: ``Surely mothers did not want to leave their children (again) when they just had become a family!''

Despite a few too many exclamation marks and drawn-out misunderstandings, all is resolved for Angel and her little brother, Rags.

Beginning readers will quickly identify with the episodic adventures in Russell Sprouts, by Johanna Hurwitz, illustrated by Lillian Hoban (Morrow, New York, $10.95, 68 pp., ages 4 to 7). Six-year-old Russell, who lives in New York City, gets lost at a movie theater, comes up with a unique Halloween costume, writes a report card for his parents, and even experiments with a bad word.

``Russell noticed that the more [his parents] complained about the word, the more he felt like saying it.'' The humor here is gentle, and the author explores familiar first-grade territory in imaginative ways.

A relationship of a different kind and time is addressed in The Friendship (Dial, New York, $11.60, 53 pp., ages 7 to 12). Author Mildred Taylor won the Newbery in 1977 for ``Roll of Thunder, Hear My Cry'' (Dial), the story of a black family living through the depression in Mississippi. That remarkable novel was based on tales her father had told of his own experience in the South, and this book is similarly drawn from a real-life incident.

Briefly, it has to do with the tenuous friendship that exists between an elderly black man, Mr. Tom Bee, and a white country-store owner, John Wallace, whose life he had saved years earlier.

Mr. Tom dares to break an unspoken code by calling John by his first name, and as a result is shot in the leg by his so-called ``friend.'' The story is told through the eyes of the Logan children, who witness the shooting. Their reactions will leave an indelible impression on readers.